The present invention relates to a new and improved construction of an arrangement for the rigid connection of a drive or driven shaft with a graduated disk of a precision measuring instrument, in particular for the rigid connection of a drive shaft with a coding disk formed of glass for an angle coding device of an abservation periscope.
In a prior art arrangement for a precision measuring instrument according to German Pat. No. 2,140,141, there are rigidly connected for rotation or torsionally resistant, for instance, at the base of a geodetic instrument two flat or planar components having mutually different temperature coefficients. Such connection between the temperature-sensitive components is formed by a number of webs arranged perpendicular to the components and having less rigidity in radial direction and greater rigidity in axial direction. In this way, a torsion or rotation-proof and to some extent elastic connection between the components is achieved. However, such known arrangement for the connection of two flat or planar components is not suitable for connecting a graduated disk or dial with a shaft.
For a precision measuring instrument there is known from German Pat. No. 2,438,146 a graduated disk formed of glass and having the graduations or scale markings arranged on the surface externally of the neutral fiber or plane. By suitably dimensioning and arranging the graduations on the graduated disk there is achieved an almost complete compensation of the graduation or scale marker errors caused by deformation and bending. The operative connection with the actual support body or carrier and related thereto the mechanical stresses at the graduated disk are not entirely or not at all eliminated in this case.